The present invention relates to tone mapping images, and more particularly, to adaptive local tone mapping high dynamic range images to low dynamic range images.
Images with a high dynamic range have a high luminance ratio between the brightest and darkest object in a scene, while images with a low dynamic range have a low luminance ratio.
When high dynamic range images are displayed on low dynamic range devices, the captured high dynamic range of the image must be compressed to the available range of the display device. This is commonly called tone mapping.
Tone mapping methods include global tone mapping and local tone mapping. Global tone mapping methods apply the same mapping function to all pixels. While global tone mapping methods provide computationally simple solutions, they often result in loss of contrast and detail. Local tone mapping methods use a spatially varying mapping function determined by the neighborhood of a pixel, which allows an increase in the local contrast and the visibility of some details of an image. Local tone mapping methods usually yield more pleasing results because human vision is more sensitive to local contrast. However, conventional local tone mapping methods may result in halo artifacts around bright areas, and increases in computation resources.
It may therefore be desirable to have improved methods for local tone mapping.